To: WG5 and J3 08-185
From: Craig Rasmussen
Subject: Request for new features from MPI Forum
Date: 2008 May 14
The MPI Forum has been restarted in order to update the Message Passing
Interface (MPI) standard. As part of this standarization effort, a new
Fortran binding will be created for version 3.0 of the MPI standard. The
MPI Forum has requested that J3 consider modifying the Fortran standard
to accomplish the following:
1. A mechanism to suppress copyin/copyout semantics for MPI
asynchronous operations.
2. Suppress argument checking for MPI choice buffers (C void * formal
parameter).
A series of straw votes were taken to determine how to address the
request from the MPI Forum. The results were:
1. The VOLATILE attribute should be given to both the actual and dummy
arguments to suppress copyin/copyout.
2. The J3 committee voted to consider three different candidates for
suppressing argument checking of C void * formal parameters. WG5 is
asked to consider this as a work item for the C Interop TR. The
candidates for the mapping of dummy argments to void * parameters
are:
a. Create a new derived type, TYPE(C_VOID), in the ISO_C_BINDING
intrinsic module.
b. Add an IGNORE(TKR) attribute for dummy arguments. This
attribute can optionally ignore any combination of type, kind,
and rank.
c. Create new syntax, TYPE(*), to allow any type actual parameter.
When combined with DIMENSION(*), this is effectively equivalent
syntax for IGNORE(TKR).